Isolation of floor machines by lever-type inertial vibration corrector

Abstract

This paper proposes and examines a lever-type vibration isolation system that is used to reduce transmitted oscillations from machines onto their floor support. This is a system with a lever mechanism for motion transformation and an auxiliary mass corrector. The substance of this mechanism is that the corrector significantly reduces oscillations from low frequency harmonic excitation by virtue of its additional inertial force. It may be used in conjunction with the classical passive isolation system when greater performance is required and when a conventional technique cannot perform adequately. With the addition of a corrector, the low frequency performance is improved overall. Some analytical results for two-degree-of-freedom (2DOF) machine-floor systems have been presented. Thereafter, the numerical analysis of the dynamic response of this system is carried out using a state space formulation approach. Extensive parametric studies have shown the effects of various levels of base flexibility, viscous damping and mass ratio on the efficiency of this isolation. The results obtained are useful for the design of lever-type isolators. In fact, the highlight of this paper is the design aspect of this novel isolator. Numerical examples of the steady-state response and the time response of two isolation systems (with and without the presence of the lever mechanism) for floor-supported industrial fans are presented. These examples illustrate the application of the formulation and the theory. Finally, the proposed isolator has been validated by dynamic testing and good agreement between theoretical and experimental results has been obtained.